Pen needle assemblies are known in the prior art. Typical construction of a pen needle assembly includes a hub to which is fixed a single needle cannula of a particular gauge. The needle cannula includes one end which extends from the hub and is formed for insertion into a patient for injection. This end constitutes a distal end of the needle cannula. The second end of the needle cannula is also exposed and is utilized to come into communication with the contents of a drug cartridge or other reservoir during an injection. This end constitutes a proximal end of the needle cannula. A lumen extends between the proximal and distal ends which provides a flow path for medicament through the needle cannula.
The needle cannula may be of various gauges, resulting in different size external cross-sections. Typically, pen needle assemblies are provided with needle cannulas being in the range of 25-32 gauge. A lower gauge number represents a cross-sectionally larger needle cannula. For example, a needle cannula of 25 gauge will have a larger external cross-section than a needle cannula of 30 gauge. Different gauge needles provide different characteristics (e.g., more buckle resistance, narrower profile, etc.). The entire needle cannula, from proximal end to distal end, is typically formed of a single gauge.